The likes of Nissan and Toyota are not heading to the Bay Area for the weather, but its unique blend of academia, innovation and investment that will be crucial in making autonomous cars road-ready.

Google's autonomous cars drive 3 million simulated miles every single day. Every time there is a code change or algorithm tweak, Google data centers relive every mile driven to date but reconstruct it with the updated software to see if the changes improve things. And that's before any of this new code is pushed out to an actual test car.

"Society tolerates a lot of human error. But we expect machines to be much better," notes Dr. Gill Pratt, Toyota Executive Technical Advisor and Chief Executive Officer of Toyota Research Institute (TRI), which officially opened its doors in the region in January to focus on developing a similar artifical intelligence capability. "The technologies we develop have to work not only at the Million-mile scale, but at the Trillion-mile scale."

In the real world, a vehicle would need to be constantly on the go for over a year to cover 1 million miles. Therefore being able to computer model and simulate test miles -- a capability that's given that Google a head start in the field -- is crucial. It's why Toyota is investing billions of dollars in AI and why Nissan is increasing its existing presence in the area. After all, autonomous cars are 90% software, acording to Maarten Sierhuis, director of Nissan's Silicon Valley Research Center. "What we are good at here is software and artificial intelligence," said Sierhuis.

The Silicon Valley ecosystem

This week Nissan opened the doors of its facilities to give some insight into the progress made and the obstacles that remain and how the area can help with solutions. "Silicon Valley is a very important place where universities, start ups, VCs and tech companies are creating a kind of ecosystem. So it's very important for us to be part of this community," said Takao Asali, Nissan's VP for Research & Advanced Engineering.

"Autonomous drive and connectivity are game changing technologies that will significantly increase safety and make consumers more productive and digitally connected while they are in their cars," said Nissan CEO, Carlos Ghosn. "Our goal is zero emission, zero fatality and the autonomous fully connected car is how we deliver that goal."

And Japanese carmakers are not the only ones with significant facilities in the area; Mercedes, Audi, BMW, Ford, GM and Hyundai are also present.

Just don't expect to see Porche here any time soon. Speaking to German newspaper Westfalen-Blatt, company CEO Oliver Blume said: "One wants to drive a Porsche by oneself. An iPhone belongs in your pocket, not on the road."